The present invention relates to a method and a system for controlling and/or regulating an engine transmission unit in a motor vehicle.
Methods and systems are provided in motor vehicles for converting a concrete torque demand at driving wheels of the motor vehicle by regulating desired values at an internal-combustion engine and/or a transmission ratio. As a rule, they therefore intervene at two points in an engine transmission unit for imaging a rotational-speed and torque range of an internal-combustion engine in a certain manner on the rotational-speed and torque range at the driving wheels of the motor vehicle corresponding to a given demand. In this case, among others, characteristic rotational speed—torque curves of the participating units should be taken into account separately.
According to the state of the art, a torque demand is defined by a respective driver of the motor vehicle, as a rule, by the position of an accelerator pedal or another input device. Various suggestions with respect to solutions are known from the field of automatic transmissions for motor vehicles with internal-combustion engines for the concrete conversion of such a torque demand. For example, in German Patent Document DE 199 49 703 C1, a method and a corresponding system are described for the continuous adjustment of each desired wheel torque in the case of an automatic range transmission. In German Patent Document DE 199 61 312 C1, an engine torque—rotational speed pair is determined as an operating point from a stored characteristic curve diagram for an infinitely variable automatic transmission depending on the driving situation and on the driver's intention. This operating point is taken as a point of intersection of the characteristic curve with a power demand hyperbola for this engine while talking into account losses determined by means of models. As relative criteria for the determination or selection of an engine operating point as the torque—rotational speed pair, the environmental and driving situation as well as the drivability, the engine-side overall efficiency, the acoustics and the driving characteristic may be entered. However, in this case, only one definition is converted by the driver as a demand, as in the case of all other methods and systems according to the state of the art,
Irrespective of the form of a respective transmission and of the type of the driving engine, in addition to the demand by the driver himself, for each possible torque demand of at least one external system, in an electronic control unit, a separate interface is provided at which the torque demand to be converted arrives. In the control device, at a corresponding point in the torque structure, depending on the type and dynamics of the demand, subsequently a decision is made by a minimal or maximal selection as to which of the demanded torques is converted. The transition from one demand to another, for example, when one of the demands is added or eliminated, takes place by way of a filter which defines certain transition gradients. Without transition gradients, the transition takes place according to defined torque buildup or torque reduction criteria which are fixedly defined in the control and/or regulation of the internal-combustion engine.
The disadvantages of this implementation essentially consist of the fact that a separate interface has to be provided in the control and/or regulation for each torque demand, and a prioritization, thus the determination as to which of the demands is finally adjusted or implemented, is fixedly coded by the maximal or minimal selection at different levels. Furthermore, the transition between different demands is implemented within the limits and definitions of a fixedly coded regulator. As a result of the increasing complexity of the overall systems in modern motor vehicles, the development expenditures of the above-described systems reach the limits of what can be mastered if there are additional expansions and/or adaptations to existing implementations. High balancing expenditures are required here in order to coordinate, when a new interface is added, its demands with those of already existing demanders and a reliable operation of the internal-combustion engine in one system.
It is therefore an object of the present invention to create a method and a system which, at acceptable costs, can be flexibly and reliably expanded and adapted to an adjustable number of demanders.
According to the invention, this object is achieved by a method or a system, which are described and claimed hereinafter.
Accordingly, in a method according to the invention, a calculation of a torque definition to be converted in each case from a defined number of demanders, which torque definition is directed at an electronic control of a driving machine and/or a transmission unit, is implemented in a separate function unit which is connected to the control. This method permits the evaluating of many different torque demands to be implemented to the control unit of a drive assembly or of an engine transmission unit according to physical and empirical aspects and then sending a torque demand to the electronic drive control unit. Thus, only one interface has to be defined in the control of the drive assembly for the torque to be set by the drive assembly, and has to be correspondingly coordinated. This coordination has to meet the dynamic requirements of the individual torque demands. The entire coordination of external torque demands takes place in the higher-ranking function unit (the master) and is therefore finally implemented by way of a single demand in the engine transmission unit or the drive assembly. All known regulating and adjusting methods and corresponding systems for the different drive assemblies can be seamlessly connected here, partly with the simplification that only one demand has to be converted. In this case, all types and models of engines/motors and transmission units can be used, such as internal-combustion, hydraulic or pneumatic drives as well as accumulator-fed electric motors or hybrid drives. In addition to automatic CVT or BIT transmissions, range transmissions can also be used as transmission units.
In a preferred embodiment of the invention, the implementation of such a master as a higher-ranking function unit takes place in three steps. First, in addition to internal torque demands, external torque demands, which are the result of different environmental and driving conditions, are considered. Then the external and internal torque demands are processed into wheel torques. Finally, the demands are prioritized, and a torque demand or torque definition is output to the electronic control of the driving machine and/or transmission unit.
In an advantageous embodiment according to the invention, a differentiation is made between the occurrence of a priority change and a progression of the respective regulating process without a priority change. In the case of a priority change, a special method is used for implementing the transition which will be explained in the following in the description by way of an example on an embodiment with reference to the drawings. Preferably, in the event of a priority change, a continuous transition is selected in the torque definition, which is determined as a function of an available time and the difference of the level of the new and of the old definition torque. In an embodiment, in a matrix for the output of the time applicable to a transition of priority demand and/or a respective curve shape are provided.
On the whole, for implementing a method according to one or more of the above-listed characteristics, a system is created in which a number of demanders can be flexibly and reliably expanded and can also be adapted with respect to their options. As a result of the definition of adapted transition functions, as a further development of the invention, in the event of a priority transition, a continuous adaptation of a torque definition takes place which is adapted to the physical characteristics of the subsequent electromechanical total system. Advantageously, on the whole, a simplification of a total control is achieved independently of the type of the engine-transmission unit and the number of torque demanders.
For illustrating additional advantages, an embodiment of the invention is described as an example in the following by means of the drawings.